Originally published 4/24/2003
“Out of the blue and into the black….”
–Neil Young singing “Into the Black” on the “Weld” album
I get a lot of questions from builders on what kind of welding machine they should buy. That’s not too tough of a question to answer, but I’ll try to make it look as hard as I can.
For welding bike frames, I use a Miller Syncrowave 350 LX which has completely adjustable weld characteristics, AC/DC, Lift Arc, built in pulser, balance/dig, the works and it’s pretty much a Cadillac machine and does everything I need it to do. But, it was expensive and way more machine than you’d ever need if you’re just welding bike frames. I use my machine for projects other than frame building, so I needed the extra flexibility the 350 offers.
See the 350LX and the rest of the Miller line at http://www.millerwelds.com/.
The quality inverter welders like the Miller Maxstars are really all you need for welding steel & titanium frames and you don’t need a pulser either but one does make life a little easier when welding thin wall tubing. What the Maxstar inverters and their ilk will not do is weld aluminum since they’re DC only and you need AC for that process. You can get inverter welders that have AC/DC capabilities like the Miller Dynasty but the price is higher than the Miller Syncrowave 250. The Syncrowave 250 will do almost everything my machine will do, as will the Syncrowave 180, but they won’t have the bells and whistles and you’ll have to buy the pulser separately if you want one. Miller offers a complete package price on the whole 9-yards.
Some may disagree, but if it came down to needing a high quality, versatile, machine I’d take the Syncrowave 250 over any of the smaller inverters if space wasn’t a heavily weighted criteria. Take a look at the 180 also as it’s less costly yet but still gives you AC capacity should you need it. Again, you need to realistically define what processes you see yourself doing and then determine what machine will support those processes. Oh, and don’t forget to check out Lincoln’s line, they make very nice machines also. I still have my old Lincoln SA200 “Pipeliner Special” engine driven welding machine with a bajillion hours on it and despite all the modern advances in welding technology, it’s still the best stick machine ever made and that Continental four cylinder engine never fails to start.
Tig Torches – Just Say NO to Air-Cooled
As far as Tig torches, I use “Welding Nozzle International” brand water-cooled torches. These are high quality, lightweight, and accept all the standard components (collets, nozzles, lenses, etc). I have three different units of varying sizes and configurations hooked to my machine via a manifold, plus a twist connect for my stick welding leads. This way I just put a tungsten in the torch I need to use and go with it without having to change anything over (if anyone decides to do this, make sure you take the tungsten out of the torches you’re not using so when you hit the foot pedal you don’t initiate an arc against your machine or what have you…an acetylene bottle would be very bad…). The torches I have on my machine are a 200-amp capacity pencil type (body and nozzle in line), a 200-amp conventional torch with a bendable head, and a 350-amp capacity conventional torch. The pencil unit is typically set up with a large diameter “Ti” type gas lens and 3/32” tungsten. This works great for tight angles like the underside of road seatstays. The smaller conventional torch I use primarily 3/32″ tungsten and whatever cup the process requires. The big torch (which I don’t use on bike frames, but for other jobs) I either use 3/32 or 1/8″ tungsten. The 200-amp conventional torch is what gets used 90% of the time.
If you decide to use a manifold setup, the manifold has to be valved to control your argon and water flow (ball valves work great for this but you can get small toggle valves like I use on my frame fixtures that work great too and look pretty spiffy when panel mounted). You don’t want your unused torches to be spitting out your expensive argon when you hit the pedal. I used to think that you should valve your water too if you use water cooled torches or you wouldn’t get sufficient coolant flow in the torch being used and would burn up your conductor as a result. In conversations I’ve had with Miller reps, their water cooler pumps are more than capable of supplying adequate flow without valving. In case you didn’t know, a water cooled torch uses a remarkably small conductor placed within the coolant supply line and the water is what keeps it from frying under welding loads.
As I said, I use a water cooler and water-cooled torches, but air-cooled is really all you need for frames and most weld processes. The advantages a water-cooled torch offers is that they’re smaller for a given amperage capacity, more flexible, and lighter, making them easier to use when having to go through the normal contortions of welding bike frames. Air-cooled torches are less expensive and demand less maintenance but I find them stiff and cumbersome since they use such large conductors to carry the amperage. Who am I kidding? I’m a tool snob. I freakin’ HATE air-cooled torches! They suck! I wouldn’t be caught dead with one! I’d sooner have “LOSER” tattooed into my forehead in huge neon letters than have to weld a bike frame with one of those POS torches!
OK, where was I? Oh, don’t bother fooling around with fingertip controls. The only time a fingertip control is beneficial is when you’re in a position where you can’t use a foot control – changing out boiler tubes, in the boiler, is a good example I keep trying to forget
Get a good foot pedal remote and train yourself to actually use it for more than an on/off switch. Its use is just as important to quality weldments as the torch and filler metal manipulations. The biggest problem beginners have is stomping on the pedal to initiate an arc and then forgetting all about it while they burn holes in their tubes…that and those stupid air-cooled torches…
It’s OK, I’m all better now….
If you’re at the point of welding a bike frame, you should already know from that you use 2% thoriated tungsten for steel and pure tungsten for aluminum and how to properly prepare them for use. 2% thoriated tungsten is marked with red for identification and pure is marked with green so that should help you keep them straight if they’re out of the container. Keep in mind that thoriated tungsten is radioactive and the dust from grinding it can be a health hazard. There are safer alternatives to using thoriated tungsten now days, lanthanated, ceriated, zirconiated and some others that are a mixture of different types. I still use thoriated for the most part and I’m comfortable with it but if you’re just starting out you should use one of the safer alternatives. Ask you local welding supplier for cut sheets and info.
As I said earlier, I primarily use 3/32” tungsten, but be aware that at normal amps used on welding steel frames, you can get a bit of arc wander with 3/32” tungsten. If this is a problem for you, you should probably use 1/16”. My welding style is to run hot and fast so it works well for me, but if you prefer to run a little slower, you may have better luck with 1/16” so you can keep your arc more focused.
I use a diamond grinding wheel designed for carbide cutter sharpening for grinding my tungsten. This particular unit has the abrasive on the side of the wheel and not the circumference as on a normal grinding wheel. You can get these for about $90 from Enco (http://www.use-enco.com ) and if you just use it for tungsten, it’ll probably last your entire frame-building career. I keep a cheap drill motor next to the grinder, chuck up the tungsten in it (by hand, not by key) and let her spin slowly while grinding the tungsten. Perfect every time. If you’re a tool snob, you can buy a special purpose tungsten grinder for around a $1,000 or so. My $29 Ryobi drill and my $90 diamond wheel works good for me.
Remember, when grinding your tungsten that the grinding lines should be close to straight from shank to point and not circular around the point or you’ll have a greater tendency for arc wander. Don’t grind your tungsten using anything that is contaminated with other metals or you’ll have problems.
For filler metals on most steel bike frame materials, you use standard 70-series, S2 rod. I was using 880T by the Weld Mold Company (insert cut sheet jpeg here) when welding stainless steel frame components (dropouts and the like) and have pretty much converted to using it on all my steel frame welds since it runs so nicely and has superior mechanical properties (something like 110ksi tensile and 35% elongation) but it does cost more…I think it’s like $14 a pound which ain’t much when you consider that a bike frame only takes about 2 or 3 pieces of .035 filler.
I like to use the very small diameter filler materials as it allows me greater flexibility on how much material I want to add and for customers who don’t like to see the welds, it helps me make them “disappear”, i.e., just enough filler to build up the joint, no more and no less and under paint the bike becomes seamless. Caveat: always achieve proper penetration and FILL the joint with filler metal so you have a net increase in weldment cross section compared to the parent metal cross section – it’s the amount of that build up beyond that that you can manipulate.
To Purge or Not To Purge
Ultra Foco tube set: $200
Assorted frame building equipment: $10,000+
Cost of argon back purge per frame: $5.00
Getting sued after the frame failed because you wanted to save $5.00: Priceless
I back purge (with your shielding gas, i.e., Argon) all my frames. I know it’s not necessary when welding out a steel bike, but I feel better about it and on some of the newer steels, I feel it’s mandatory.
In my opinion it’s a false economy to try to save the $5 by eliminating the back purge on any high performance steel frame. If you’re using some of the more exotic steel tubes that are already pushing the envelope on wall thickness, why take chances by not back purging? Proper back purging with Argon will eliminate the scaling and oxidation and much of the swelling associated with Tig welding thin wall members. Here’s a simple experiment you can do at home:
- Properly prep two pieces of thin wall tubing.
- Join the pieces using a back purge and you’ll note the normal discoloration of the tubes at the weld joint and you should see bright, even, stitching on the ID of the tube (if you’re welding thicker members, you may only see the discoloration).
- Repeat #2 above without back purge. You will see significant scaling and oxidation in the ID of the tubes, you may see pockmarks, or even porosity depending on the materials joined. If you’re welding stainless members, you’ll see black “sugaring”, if on Ti, you’ll see your customer’s life pass before your eyes.
Remember that any surface discontinuity can be a stress riser and a source for failure. If you have surface scaling, you ARE reducing the member’s wall thickness. You don’t need back purge on thicker tube sets, but when it comes to less than .8mm butts and high performance steel alloys, you’ll be better off spending the extra $5.
BTW, if you’re welding on stainless dropouts and not back purging the weld you’re flirting with disaster.
Gloves – I use Kevlar gloves that cost about $4 a pair. These are the greatest things since sliced bread for the Tig welder.
I use two different kinds of Kevlar gloves. I buy them both from Enco http://www.use-enco.com. I use the heavy black Kevlar gloves (Enco part number 505-4134) for welding structural steel stuff like fixture stands and I use them for welding aluminum, because as anyone who welds aluminum knows it transfers heat well and I’m not smart enough to keep my hands away from it. For welding steel or ti, I use the Golden Needle Kevlar gloves (Enco part number 505-4135). These are a lighter glove, they’re gold in color and they show dirt well which is a good thing when frame building. They’re washable. They last a looooong frickin’ time (months). They don’t absorb oils unless you’re serious about it. They fit your hand well if you have average size hands. They don’t burn unless you do something really stupid and if you do something really stupid, they won’t shrink on your burning fingers like leather gloves do. They also don’t conduct heat and this is important if you have a “dang near holding the cup” welding style like I do. They cost less than $4 a pair if you buy $40-odd bucks worth. IMO, they are vastly superior to any leather glove (and I’ve used them all) for Tig welding. I give them two tungstens up!